[Sbs_gems] [EXTERNAL] Re: [Revised Logentry] SBS GEM HV Issue

[Sean Jeffas]

Hi All,

After some more work we have decided that the HV channel is probably
broken. So we will need to make an access to the hall to fix this. It is
not critical for GEn so we will leave these two SBS GEMs off and wait for
the next hall access.

Best,
Sean

On Wed, Feb 15, 2023 at 3:20 PM jeffas--- via Sbs_gems <sbs_gems at jlab.org>
wrote:

> SBS GEM HV Issue <https://logbooks.jlab.org/entry/4131946>
>
>    - Edit
>    <https://logbooks.jlab.org/entry/4131946/edit?destination=email/send>
>    - Delete
>    <https://logbooks.jlab.org/entry/4131946/delete?destination=email/send>
>
> Lognumber 4131946 <https://logbooks.jlab.org/entry/4131946>. Submitted by
> jeffas <https://logbooks.jlab.org/user/jeffas> on Wed, 02/15/2023 - 14:52
> <https://logbooks.jlab.org/entries?start_date=1676487169&end_date=1676494369&book=HALOG>.
>
>
> Last updated on Wed, 02/15/2023 - 15:17
> Logbooks: HALOG <https://logbooks.jlab.org/book/halog>
> Backlinks: UVa SBS GEMs on except L2 M0 & M1
> <https://logbooks.jlab.org/entry/4131957>
>
> I noticed that two SBS GEM voltages started drifting. See the attached
> plots below. These two GEMs are physically next to each other on the HV
> power supply and on the detector stack. You can see that M0 drifts down
> while M1 drifts up. At some point M1 trips. Then I try to turn it back on
> and it goes back to drifting upward again. Then I try turning off HV on
> both modules, and M1 turns off but M0 refuses to turn off and continues
> drifting. I turned all of SBS GEMs off and you can see in run 4173 that M0
> is clearly still on, https://logbooks.jlab.org/entry/4131954 (also look
> at the plot below. For now I will leave M0 and M1 off ad keep all other SBS
> GEMs on.
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